SYNOPSIS
xd [OPTIONS] arguments
DESCRIPTION
The program xd is used to perform eXtra fast Directory changes. Usually to change a directory the user is required to enter a command like, e.g., cd /usr/local/bin, possibly with the aid of shell completion. In many cases this is a tedious task: shell completion shows all entries, including files, when we're only interested in directories and the full specification of our intented directory may eventually require many keyboard actions.
Xd was designed a long time ago (in the early 90s) to reduce the effort of changing a directory. Often we're well aware to which directory we want to change, and it's easy to produce the initial directory characters of that directory. E.g., if the intent is to cd to /usr/local/bin, it's rather easy to produce the letters ulb.
Xd capitalizes on this capability. By providing the initial directory characters of directories xd determines the proper expansion allowing you to change directories fast. So, entering the command xd ulb results in the expansion /usr/local/bin.
Often life is not that easy. Often there are multiple expansions from a given set of initial characters. E.g., when entering xd ulb xd may find several alternatives. E.g.,
1: /usr/lib/base-config
2: /usr/lib/bonobo
3: /usr/lib/bonobo-activation
4: /usr/local/bin
If these are the alternatives, this is exactly what xd will show
you. Then, by simply pressing the 3 key (no Enter key required)
xd will produce the required /usr/local/bin.
Commands to xd can be specified so as to fine-tune xd's behavior:
- By default (as specified by the configuration file, see below) expansions may start at the user's home directory or at the system's root directory.
- Initial character /: If the first character of the command is / then all expansions are performed from the system's root directory. E.g., xd /t results in /tmp but not in /home/user/tmp.
- Initial character .: If the first character of the command is . then all expansions are performed from the user's home directory. E.g., xd .t results in /home/user/tmp but not in /tmp
- Initial character 0: If the first character of the command is 0, then all expansions start at the current working directory. In fact, this is a specialization of the following, more general form:
- Initial character 1..9: If the first character of the command is a digit between 1 and 9 then all expansions start at that parent directory level of the current working directory (up to the system's root directory). E.g., if the current working directory is /usr/share/doc then xd 2lb will offer the alterative /usr/local/bin: two steps up, then look for directories starting with l and therein directories starting with b.
-
Separators (space, forward slash and underscore ( , / and _)):
sometimes it is clear that there are many alternatives and the intention is to
reduce that number. By using a separator subsequently nested directories must
start with the characters between the separators. E.g., xd u l bi will not
produce the alternative /usr/lib/base-config anymore, since
base-config does not start with bi. In this case only
/usr/local/bin is produced. Separators may be mixed (xd u/l bi is
identical to xd u l bi). Since the / can also be used as a
root-directory specification, a conflict is implied by a command like xd /u
l bi. This conflict is solved by given the initial character a higher
precedence than the separator. Using the underscore (_) separator in this case
is another way to solve the conflict (which in practice hardly ever occurs).
If there's only one solution, Xd writes that directory to its standard output stream. If there are multiple solutions, then a list of at most 62 alternatives (10 for the numbers 0..9, 26 for the letters a..z and 26 for the letters A..Z) is written to the standard error stream from which the user may select an alternative by simply pressing the key associated with the selection of choice. If no selection is requested any other key may be pressed (e.g., the space bar or the Enter key). If there is no solutioon xd writes the text No Solutions to the standard error stream.
When xd is given at least one argument, all its output is sent to the standard error stream, but for the selected directory name which is written to the standard output stream. If no selection is made or if the selection process is aborted a single dot is written to the standard output stream. Usually xd will be called by a shell alias, providing the cd command with xd's output (see below at the SHELL SCRIPTS section) executing cd `xd $*`. The default dot produced by xd prevents an unintended change of directory.
If xd is called without arguments then usage information is written to the standard error stream.
Xd may be further configured using options and a configuration file, discussed in the OPTIONS and CONFIGURATION FILE sections below.
GENERALIZED DIRECTORY SEARCH
Starting with version 3.10.0 xd also supports generalized directory search command processing (GDS). When GDS is requested separators are no longer required, and xd will find all possible alternatives resulting from all possible sequential combinations of the initial search command. GDS is activated either by specifying the -g command line flag or by entering generalized-search in xd's configuration file. Alternatively, when the latter is specified then the --traditional command line option will suppress GDS.
When using GDS each initial substring of the command to xd is considered as the initial characters of a directory. E.g., if the command xd tmps is entered using GDS then directories matching the following search patterns will be found;
- /t*/m*/p*/s*/
- /t*/m*/ps*/
- /t*/mp*/s*/
- /t*/mps*/
- /tm*/p*/s*/
- /tm*/ps*/
- /tmp*/s*/
- /tmps*/ Using the traditional processing mode only the first one of these alternative patterns is considered.
Multiple command line arguments, the slash and the underscore can still be used with GDS in which case they force a directory change in the considered patterns. E.g., with the command xd tm/ps the following patterns will be considered:
- /t*/m*/p*/s*/
- /t*/m*/ps*/
- /tm*/p*/s*/
- /tm*/ps*/ In this set all of the previous patterns showing the ...mp... combination were dropped, as a directory change is forced between the m and p characters.
RETURN VALUE
Xd returns 0 to the operating system unless an error occurs (e.g., when a non-existing configuration file is specified), or xd's version or usage info is shown or requested.
OPTIONS
If available, single letter options are listed between parentheses following their associated long-option variants. Single letter options require arguments if their associated long options require arguments as well.
-
--add-root condition
If the search starts at the user's home directory an additional search starting at the system's root directory may be performed as well, depending on the value specified for the add-root option. Alternatives are never (no additional search is performed); if-empty (an additional search is performed if the initial search did not yield any directory); or always (an additional search is always performed). There is also a configuration file directive add-root (see below). -
--all -a
If the configuration file (see below) contains ignore directives then these directives are ignored when computing the alternatives from which the user may select a directory to change to. -
--config-file=filename (-c)
The name of an xd configuration file. By default xd looks for the file .xdrc in the user's home directory. The existence of the default file is optional. -
--directories inclusion
Directories may be also be reached via symbolic links. The inclusion type all adds these symbolic links to the list of alternatives. The inclusion type unique prevents symbolic links from being added to the list of alternatives. There is also a configuration file directive directories (see below). -
--generalized-search -g
When this option is specified xd uses GDS unless the directive traditional is specified in the configuration file. -
--help (-h)
Basic usage information is written to the standard error stream. -
--history [filename]
A history of previously made choices is kept in the file filename. If --history is specified, but the filename is left empty the history file $HOME/.xd.his is used. This file should only be modified by xd itself. If you can't resist editing it then use the following example showing the format of the lines in the history file.1292596154 1 /home/frank/svn/xd/The first field is the time (in seconds since the epoch) the entry was written, the second field is the number of times the entry has been selected and the third field is the associated path. -
--history-lifetime spec
The lifetime of the entries in the history file. The specification consists of a number followed by D, W, M or Y, representing, resp. days, weeks, months, or years. A month is considered a period of 30 days, a year a period of 365 days. If the specification is omitted a lifetime of 1M (one month) is used. Entries older than history-lifetime are disregarded as history-items and are removed from the history file. -
--history-maxsize nr
The maximum number of entries the history file may contain. By default there is no limit. When history-maxsize is specified and more than the maximum number of history items are found in the history file then the nr most popular choices are kept. Usually the cut-off point will be somewhere within a popularity category. In that case the most recently selected alternatives within that category are kept. -
--history-position [top|bottom]
When this option is specified then previously found alternatives are displayed either at the top of the list or at the bottom of the list. If this option is omitted then the elements in the history will be intermixed with new alternatives. The next option history-separate is only used when this option is also specified. By merely specifying history-position the history items are shown at the top of the list. -
--history-separate
When specified, a blank line is written between the items in the history and new alternatives (not previously selected). This option is only interpreted when the previous option is also specified. -
--icase -i
This option is used to specify case-insensitive pattern matching. E.g., specifying xd /ub returns the directory /usr/bin, but not a directory like /UnSpecified/Books, which is returned by xd /UB. However, xd -i /ub (using any letter casing for the specification) returns both directories. The option icase could of course be specified in the configuration file, which which case case-insensitive matching is used by default. In the latter case specifying -i as a command line option reverts the matching procedure to case-sensitive directory matching. In general, when an even number of icase specifications is provided xd uses case-sensitive directory matching, while an odd number of icase specifications results in case-insensitive directory matching. -
--start-at origin
Defines the default start location of directory searches. Origin home results in all default searches to start at the user's home directory. Origin root results in searches to begin at the disk's root (/) directory. There is also a configuration file directive start-at (see below). -
--traditional
When this option is specified xd will not use GDS but will use its traditional mode. It overrules a generalized-search directive specified in the configuration file as well as the -g option. -
--verbose (-V)
More extensive information about the actions taken by the xd program is written to the standard error stream. -
--version (-v)
Xd's version number is written to the standard error stream.
CONFGURATION FILE
The default configuration file is .xdrc in the user's home directory. It may be overruled by the program's --config-file option.
Empty lines are ignored. Information at and beyond #-characters is interpreted as comment and is ignored as well.
All directives in xd configuration files follow the pattern
directive value
but for some directives value is optional.
A line may at most contain one directive, but white space (including comment at the end of the line) is OK. The same directive may be specified multiple times, in which case the last directive will be used (with the exception of the ignore directive, see below). All directives are interpreted case sensitively. Non-empty lines not beginning with a recognized directive are silently ignored.
The following directives can be used in the configuration file. Default values are shown between parentheses.
-
add-root when (if-empty)
If the search starts at the user's home directory an additional search starting at the system's root directory may be performed as well, depending on the value specified for the add-root directive.
If when is specified as always then an additional search is always performed.
If it is specified as if-empty then an additional search is performed if the initial search (starting at the user's home directory) did not yield any directory.
If it is specified as never no additional search is performed.
This directive is overruled by the ---add-root command line option. -
directories which (all)
Directories may be also be reached via symbolic links. The specification all will add these symbolic links to the list of alternatives. The specification unique will prevent the symbolic links from being added to the list of alternatives.
This directive is overruled by the ---directories command line option. -
generalized-search
When this directive is specified xd will use GDS by default. -
history [filename]
A history of previously made choices is kept in the file filename. If history is specified, but the filename is left empty the history file $HOME/.xd.his is used. This file should only be modified by xd itself. If you can't resist editing it then use the following example showing the format of the lines in the history file.1292596154 1 /home/frank/svn/xd/The first field is the time (in seconds since the epoch) the entry was written, the second field is the number of times the entry has been selected and the third field is the associated path. -
history-lifetime spec
The lifetime of the entries in the history file. The specification consists of a number followed by D, W, M or Y, representing, resp. days, weeks, months, or years. A month is considered a period of 30 days, a year a period of 365 days. If the specification is omitted a lifetime of 1M (one month) is used. Entries older than history-lifetime are disregarded as history-items and are removed from the history file. -
history-maxsize nr
The maximum number of entries the history file may contain. By default there is no limit. When history-maxsize is specified and more than the maximum number of history items are found in the history file then the nr latest choices are kept. Each previously made selection counts as one. If a new alternative is selected it always becomes an element in the history list. -
history-position [top|bottom]
When specified alternatives found in the history will be displayed either at the top of the list or at the bottom of the list. If this option is omitted then the elements in the history will be intermixed with new alternatives. The next directive history-separate is only used when this directive is also specified. By merely specifying history-position the history items are shown at the top of the list. -
history-separate
When specified, a blank line is written between the items in the history and new alternatives (not previously selected). This directive is only interpreted when the previous directive is also specified. -
--icase -i
This specification is used to request case-insensitive pattern matching. If this option is entered in the configuration file then specifying xd /ub returns the directory /usr/bin as welll as a directory like (assuming it exists) /UnSpecified/Books. When specified in the configuration file, the command-line option -i reverts the matching procedure back to case-sensitive directory matching. In general, when an even number of icase specifications is provided xd uses case-sensitive directory matching, while an odd number of icase specifications results in case-insensitive directory matching. -
ignore path
The configuration file may contain multiple ignore directives which are --different from the way other directives are handled-- all interpreted. Each ignore directive is followed by a path specification as shown in a list of alternatives produced by xd or an initial substring of such a path terminating in a * character. When xd encounters a path matching any of the ignore directives (with the * interpreted as `any further directory name' specification) it will not display that path in its list of alternatives. This directive is overruled by the ---all command line option. -
start-at value (home)
Defines the default start location of directory searches. Values are home and root. When home is specified all searches start at the user's home directory. When root is specified searches start at the disk's root (/) directory. If the directory is omitted or if another value is specified then the default is used, which is home. This directive is overruled by the ---start-at command line option. -
traditional
This directive may be used to request the use of xd's traditional mode. It overrules the -g command line option and the generalized-search directive. )
SHELL SCRIPTS
Assuming xd is installed in /usr/bin scripts can be defined around xd for various shell programs. This allows the shell to change directories under control of xd.
To use xd with the bash(1)-shell, the following function can be used (which could be added to, e.g., .bash_login):
xd() # function to do `cd` using `xd`
{
cd "`/usr/bin/xd $*`"
}
To use xd with the tcsh(1)-shell, the following alias can be added to, e.g., the ~/.alias file:
alias xd 'cd `\xd \!*`'
If your system uses blanks in directory names, the above tcsh-alias cannot
be used as the blanks are interpreted as argument-separaters. In that case the
following alias can be defined:
alias xd 'setenv XD "`\xd \!*`";cd "$XD"'
Having defined the xd alias or script xd ... commands results in the automatic (or optional) change of the current working directory
EXAMPLES
xd ulb - all directories starting subsequently,
with u, l and b origin is default, or
specified in .xdrc as home or root
xd 0t - all directories starting with t below the cwd
xd 2t - all directories starting at the `grandparent'
(2 steps up) of the cwd
xd --start-at root t
- all directories at the root starting with t
xd .. - all directories starting with a dot in the cwd
Assuming the following directories exist:
/usr/lib/bonobo
/usr/lib/bonobo-activation
/usr/local/bin
then the following two ignore specifications in xd's configuration
file will result in ignoring the bonobo directory alternatives:
First specification:
ignore /usr/lib/bonobo
ignore /usr/lib/bonobo-activation
Second specification:
ignore /usr/lib/bonobo*
FILES
- $HOME/.xdrc: Default location of the configuration file
-
https://fbb-git.github.io/xd/: Home directory
BUGS
None reported
ABOUT xd
The program xd was initially (before 1994) written for the MS-DOS platform. In 1994 it was designed to work under Unix (Linux, AIX) and it was converted to C++. The original C++ code is still available (https://oosix.icce.rug.nl/svnroot/xd/tags/start/xd/) and is funny to look at as it is a remarkable illustration of C++ code written by C programmers who had just learned about C++. Versions 2.x have been used until 2008, and in late August 2008 I rewrote xd completely, reflecting my current views about C++, resulting in versions 3.x.y and beyond. The 3.x.y and later versions extensively use the facilities offered by the bobcat(7) library.
ACKNOWLEDGEMENTS
GDS was added to xd following a suggestion by Bram Neijt (bram at neijt dot nl).